# Indicated probability

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Indicated probability refers to the probability of a specified event occurring.

For example, suppose that two coins are tossed and we wish to find the probability of getting two heads. We have four possible outcomes {HH, HT, TH, TT} out of which possibility HH is the specified/indicated event. Here the indicated event has a one out of four chance of occurring and therefore,

Indicated probability = ¼ =0.25

So we see that the indicated probability can be calculated by the formula,

Example 1: Suppose that dice is thrown. Find the probability of getting an even number.

Solution: Here the indicated event is getting an even number. The favourable outcomes are getting 2, 4, and 6 on the face of the dice.

There are a total of 6 outcomes of which 3 are favourable and hence by the above formula,

Indicated Probability = 3/6 = ½ = 0.5

The above example involved calculating dice roll probabilities.

Let us now consider an example of calculating coin toss probabilities.

Example 2: Suppose that two coins are tossed. Find the probability of getting exactly one head.

Solution: Here the indicated event is getting exactly one head. We have four possible outcomes {HH, HT, TH, TT}.

The favourable outcomes are {HT, TH}

There are a total of 4 outcomes of which 2 are favourable and hence by the above formula,

Indicated Probability = Number of favourable outcomes/Number of total outcomes = 2/4 = ½ = 0.5

### Additional Rules to calculate indicated probabilities:

1. Multiplication rule to calculate probability
2. Addition rule to calculate P(A or B) that is, to calculate the probabilities of occurrence of either event A or event B

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